1. Field of the Invention
The present invention relates to a portable apparatus, including but not limited to a cellular phone, a notebook computer, a smart phone, a PDA, a game machine or the like, and more particularly to a gear hinge device that provides two parallel hinge axes for opening and closing opposed portions of a folder type portable apparatus by rotation about two parallel axes.
2. Description of the Related Art
Among various types of portable apparatuses classified by appearances, a folder-type portable apparatus essentially includes a hinge device for rotatably connecting two housings. The hinge device may be configured to provide either a single hinge axis or two hinge axes. That is, the hinge device may be employed in a portable apparatus as a single-axis hinge device for providing a single hinge axis or as a dual-axis hinge device for providing two hinge axes, in this way the two opposed portions of the folder type portable apparatus may open and close by rotating about a single axis or by rotation about two parallel axes.
In general, a hinge device employed in a folder-type portable apparatus essentially employs a cam unit (a driving cam and a driven cam), and an elastic member to provide a stopping angle of the housing of the portable apparatus as being rotated, and offers convenience to a user when opening/closing the portable apparatus by incorporating the cam action between the elastic member and the driving and driven cams of the cam unit. In order to provide convenience to the user for opening/closing the portable apparatus, it is preferable that the hinge device should provide a force for continuously maintaining the folder type portable apparatus in a closed state when it is closed. Likewise, the hinge device should provide a force for opening the portable apparatus by a first predetermined angle or more, and the hinge device should also provide a force for stopping the folder at a second predetermined angle.
A dual-axis hinge device is disclosed in the publication of Korean Utility Model Registration No. 20-0439610 (Application No. 20-2007-0002620).
However, the hinged cover opening/closing device disclosed in the prior art utility model publication has a problem in that even if there is a minute deviation that occurs at a peak of the gear teeth, then a deviation may be caused in the opening/closing movement of the folder type portable apparatus and thus disrupt the smooth opening/closing movement of the folder, and thus will deteriorate the reliability of the final product.
In addition, the hinged cover opening/closing device disclosed in that prior art utility model publication has a further problem in that the gear unit employed therein is fabricated through die-casting process, which will cause an increase of manufacturing costs.
Therefore, the present invention is intended to provide a stable opening/closing movement (a smooth opening/closing movement) of a dual-axis hinge device that is inexpensive to manufacture and implement.